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Cascaded Long Term Prediction of Polyphonic Signals for Low Power Decoders

An optimized cascade of long term prediction filters, each corresponding to an individual periodic component of the polyphonic audio signal, was shown in our recent work to be highly effective as an inter-frame prediction tool for low delay audio compression. The earlier paradigm involved backward adaptive parameter estimation, and hence significantly higher decoder complexity, which is unsuitable for applications that pose a stringent power constraint on the decoder. This paper overcomes this limitation via extension to include forward adaptive parameter estimation, in two modes that trade complexity for side information: (i) a subset of parameters is sent as side information and the remaining is backward adaptively estimated; (ii) all parameters are sent as side information. We further exploit inter-frame parameter dependencies to minimize the side information rate. Objective and subjective evaluation results clearly demonstrate substantial gains and effective control of the tradeoff between rate-distortion performance and decoder complexity.